83
Effects of Substrata
As in the preceeding chapter, both unpurified and
purified A2B5(-) cells were cultured on substrata of either
glass or polyornithine. It was found that although there
were slight differences in the development of monolayers
with regards to the extent of cell aggregation before
spreading, polyornithine was not found to be selective for
neurons as it was with day 7 and 8 cells. No cell phenotype
that was observed to develop on glass was absent from
monolayers on polyornithine. Thus, the degeneration of
glial precursors on polyornithine was not manifested in
day 12 and 13 cells.
A2B5 Antigen Modulation
By the immunofluorescent assay described here and in
the preceedind chapter, the immunomagnetic separations
resulted in extremely purified populations of A2B5(-)
cells. Unpurified cells were approximately 45% A2B5(+)
(Fig.3-3). Purified cells were virtually free of A2B5(+)
cells, with a typical purity of >99.99% A2B5(-). After one
day in vitro, however, large numbers of A2B5(+) cells
(=80%) were present in the cultures of initially purified
cells (Fig.3-3). No increase in A2B5(+) cells was observed
in cultures made from unpurified cells. Thus, A2B5 antigen
is apparently modulated on the surfaces of the majority of
A2B5(-) cells in purified cultures, but not on the surfaces
of A2B5(-) cells in unpurified cultures. Plating